Purification Of Bio Based Acrylic Acid To Crude And Glacial Acrylic Acid

ABSTRACT

Processes for the purification of bio-based acrylic acid to crude and glacial acrylic acid are provided. The bio-based acrylic acid is produced from hydroxypropionic acid, hydroxypropionic acid derivatives, or mixtures thereof. The purification includes some or all of the following processes: extraction, drying, distillation, and melt crystallization. The produced glacial or crude acrylic acid contains hydroxypropionic, hydroxypropionic acid derivatives, or mixtures thereof as an impurity.

FIELD OF THE INVENTION

The present invention generally relates to the production of crude andglacial acrylic acid from bio-based acrylic acid produced fromhydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof. More specifically, the invention relates to the purification ofbio-based acrylic acid to crude and glacial acrylic acid using some orall of the extraction, drying, distillation, and melt crystallizationprocesses. The produced crude and glacial acrylic acid containshydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof as an impurity.

BACKGROUND OF THE INVENTION

Acrylic acid or acrylate has a variety of industrial uses, typicallyconsumed in the form of polymers. In turn, these polymers are commonlyused in the manufacture of, among other things, adhesives, binders,coatings, paints, polishes, detergents, flocculants, dispersants,thixotropic agents, sequestrants, and superabsorbent polymers, which areused in disposable absorbent articles including diapers and hygienicproducts, for example. Acrylic acid is commonly made from petroleumsources. For example, acrylic acid has long been prepared by catalyticoxidation of propylene. These and other methods of making acrylic acidfrom petroleum sources are described in the Kirk-Othmer Encyclopedia ofChemical Technology, Vol. 1, pgs. 342-369 (5^(th) Ed., John Wiley &Sons, Inc., 2004). Petroleum-based acrylic acid contributes togreenhouse emissions due to its high petroleum derived carbon content.Furthermore, petroleum is a non-renewable material, as it takes hundredsof thousands of years to form naturally and only a short time toconsume. As petrochemical resources become increasingly scarce, moreexpensive, and subject to regulations for CO₂ emissions, there exists agrowing need for bio-based acrylic acid or acrylate that can serve as analternative to petroleum-based acrylic acid or acrylate. Many attemptshave been made over the last 40 to 50 years to make bio-based acrylicacid or acrylate from non petroleum sources, such as lactic acid (alsoknown as 2-hydroxypropionic acid), 3-hydroxypropionic acid, glycerin,carbon monoxide and ethylene oxide, carbon dioxide and ethylene, andcrotonic acid.

Petroleum-based acrylic acid is produced by theheterogeneously-catalyzed gas-phase oxidation of propylene with the useof molecular oxygen. Typical side products in this process are carbonylcompounds, such as, benzaldehyde, furfurals, propionaldehyde, etc., andacids or anhydrides, such as, formic acid, propanoic acid, acetic acid,and maleic acid, or maleic anhydride. The typical composition in wt % ofa reaction gas coming out of the process is (see U.S. Pat. No. 7,179,875(issued in 2007)): acrylic acid up to 30%, steam up to 30%, carbonoxides up to 15%, nitrogen up to 90%, oxygen up to 10%, propylene up to1%, acrolein up to 2%, propane up to 2%, formic acid up to 1%, aceticacid up to 2%, propionic acid up to 2%, aldehydes up to 3%, and maleicanhydride up to 0.5%.

Depending on the end use, there are two purity levels of acrylic acid:crude acrylic acid (also called technical grade acrylic acid) andglacial acrylic acid. Crude acrylic acid has a typical minimum overallpurity level of 94% and is used to make acrylic esters for paint,adhesive, textile, paper, leather, fiber, and plastic additiveapplications. Glacial acrylic acid has a typical overall purity levelranging from 98% to 99.7% and is used to make polyacrylic acid forsuperabsorbent polymer (SAP; in disposable diapers, training pants,adult incontinence undergarments, etc.), paper and water treatment, anddetergent co-builder applications. The levels of the impurities need tobe as low as possible in glacial acrylic acid to allow for a high-degreeof polymerization to acrylic acid polymers (PAA) and avoid adverseeffects of side products in applications. For example, aldehydes hinderthe polymerization and also lead to discoloration of the polymerizedacrylic acid; maleic anhydride forms undesirable copolymers which have adetriment to the polymer properties; and carboxylic acids, that do notparticipate in the polymerization, might affect the final odor of PAA orSAP or provide adverse effects in the use of the products, e.g. skinirritation when the SAP contains formic acid, or odor when the SAPcontains acetic acid or propionic acid. To remove or reduce the amountsof side products from petroleum-based acrylic acid and produce eitherpetroleum-based crude acrylic acid or petroleum-based glacial acrylicacid, multistage distillations and/or extraction and/or crystallizationssteps were employed in the prior art (e.g. see U.S. Pat. Nos. 5,705,688(issued in 1998), and 6,541,665 (issued in 2003)).

Bio-based acrylic acid, produced from renewable feedstocks orintermediate chemicals (e.g. lactic acid or lactate, glycerin,3-hydroxypropionic acid or its ester, etc.), has different impurityprofiles and levels than petroleum-based acrylic acid. For example, whenlactic acid is used as the intermediate chemical, the major impuritiesare acetaldehyde, acetic acid, lactic acid, and propanoic acid.Nevertheless, the minimum overall purity levels of bio-based crudeacrylic acid and bio-based glacial acrylic acid required for the finalapplications from bio-based acrylic acid are expected to be the same asthose in petroleum-based acrylic acid, i.e., 94% and 98%, respectively.

Accordingly, there is a need for commercially viable processes to purifybio-based acrylic acid produced from the dehydration of hydroxypropionicacid, hydroxypropionic acid derivatives, or mixtures thereof, to crudeor glacial acrylic acid.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, a glacial acrylic acidcomposition is provided comprising at least about 98 wt % acrylic acid,and wherein a portion of the remaining impurities in said glacialacrylic acid composition is hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof.

In another embodiment of the present invention, a glacial acrylic acidcomposition is provided produced by the steps comprising:

-   -   a. Providing an aqueous solution of acrylic acid comprising: 1)        acrylic acid; and 2) lactic acid, lactic acid derivatives, or        mixtures thereof, and wherein said aqueous solution of acrylic        acid is essentially free of maleic anhydride, furfural, and        formic acid;    -   b. Extracting said aqueous solution of acrylic acid, with a        solvent to produce an extract;    -   c. Drying said extract to produce a dried extract;    -   d. Distilling said dried extract to produce distilled acrylic        acid composition;    -   e. Cooling said distilled acrylic acid composition to a        temperature from about −21° C. to about 14° C. to produce        crystals of acrylic acid;    -   f. Partially melting said crystals of acrylic acid to produce a        liquid/solid mixture;    -   g. Decanting said liquid/solid mixture to produce a purified        acrylic acid solid composition;    -   h. Fully melting said purified acrylic acid solid composition to        produce a purified acrylic acid liquid composition; and    -   i. Determining the acrylic acid purity of said purified acrylic        acid liquid composition, and if the purity is less than about 98        wt % acrylic acid, repeating said cooling, partially melting,        decanting, and fully melting steps on the purified acrylic acid        liquid composition until a purity of about 98 wt % acrylic acid        is achieved and said glacial acrylic acid composition is        produced.

In yet another embodiment of the present invention, a glacial acrylicacid composition is provided produced by the steps comprising:

-   -   a. Providing an aqueous solution of acrylic acid comprising: 1)        acrylic acid; and 2) lactic acid, lactic acid derivatives, or        mixtures thereof, and wherein said aqueous solution of acrylic        acid is essentially free of maleic anhydride, furfural, and        formic acid;    -   b. Extracting said aqueous solution of acrylic acid with a        solvent to produce an extract;    -   c. Drying said extract to produce a dried extract;    -   d. Distilling said dried extract to produce a distilled acrylic        acid composition; and    -   e. Determining the acrylic acid purity of said distilled acrylic        acid composition, and if the purity is less than about 98 wt %        acrylic acid, repeating said distilling step on the purified        acrylic acid composition until a purity of about 98 wt % acrylic        acid is achieved and said glacial acrylic acid composition is        produced.

In one embodiment of the present invention, a crude acrylic acidcomposition is provided comprising between about 94 wt % and about 98 wt% acrylic acid, and wherein a portion of the remaining impurities insaid crude acrylic acid composition is hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof, is provided.

In another embodiment of the present invention, a crude acrylic acidcomposition is provided produced by the steps comprising:

-   -   a. Providing an aqueous solution of acrylic acid comprising: 1)        acrylic acid; and 2) lactic acid, lactic acid derivatives, or        mixtures thereof, and wherein said aqueous solution of acrylic        acid is essentially free of maleic anhydride, furfural, and        formic acid;    -   b. Extracting said aqueous solution of acrylic acid with a        solvent to produce an extract;    -   c. Drying said extract to produce a dried extract;    -   d. Distilling said dried extract to produce a distilled acrylic        acid composition; and    -   e. Determining the acrylic acid purity of said distilled acrylic        acid composition, and if the purity is less than about 94 wt %        acrylic acid, repeating said distilling step on the purified        acrylic acid composition until a purity of about 94 wt % acrylic        acid is achieved and said crude acrylic acid composition is        produced.

In yet another embodiment of the present invention, a crude acrylic acidcomposition is provided produced by the steps comprising:

-   -   a. Providing an aqueous solution of acrylic acid comprising: 1)        acrylic acid; and 2) lactic acid, lactic acid derivatives, or        mixtures thereof, and wherein said aqueous solution of acrylic        acid is essentially free of maleic anhydride, furfural, and        formic acid;    -   b. Extracting said aqueous solution of acrylic acid with a        solvent to produce an extract;    -   c. Drying said extract to produce a dried extract;    -   d. Distilling said dried extract to produce a distilled acrylic        acid composition;

e. Cooling said distilled acrylic acid composition to a temperature fromabout −21° C. to about 14° C. to produce crystals of acrylic acid;

-   -   f. Partially melting said crystals of acrylic acid to produce a        liquid/solid mixture;    -   g. Decanting said liquid/solid mixture to produce a purified        acrylic acid solid composition;    -   h. Fully melting said purified acrylic acid solid composition to        produce a purified acrylic acid liquid composition; and    -   i. Determining the acrylic acid purity of said purified acrylic        acid liquid composition, and if the purity is less than about 94        wt % acrylic acid, repeating said cooling, partially melting,        decanting, and fully melting steps on the purified acrylic acid        liquid composition until a purity of about 94 wt % acrylic acid        is achieved and said crude acrylic acid composition is produced.

In one embodiment of the present invention, a glacial acrylic acidcomposition is provided comprising about 99 wt % acrylic acid, producedby the steps comprising:

-   -   a. Providing an aqueous solution of acrylic acid comprising: 1)        from about 8 wt % to about 16 wt % acrylic acid; and 2) from        about 0.1 wt % to about 10 wt % lactic acid, lactic acid        derivatives, or mixtures thereof, and wherein said aqueous        solution of acrylic acid is essentially free of maleic        anhydride, furfural, and formic acid;    -   b. Extracting said aqueous solution of acrylic acid, with ethyl        acetate to produce an extract;    -   c. Drying said extract with sodium sulfate to produce a dried        extract;    -   d. Vacuum distilling said dried extract at about 70 mm Hg and        40° C. to produce a distilled crude acrylic acid composition;    -   e. Fractionally distilling said distilled crude acrylic acid        composition at about 40 mm Hg and collecting fractions from        59° C. to 62° C. to produce a distilled acrylic acid        composition;    -   f. Cooling said distilled acrylic acid composition to a        temperature from about 0° C. to about 5° C. to produce crystals        of acrylic acid;    -   g. Partially melting said crystals of acrylic acid to produce a        liquid/solid mixture;    -   h. Decanting said liquid/solid mixture to produce a purified        acrylic acid solid composition;

i. Fully melting said purified acrylic acid composition to produce apurified acrylic acid liquid composition; and

-   -   j. Determining the acrylic acid purity of said purified acrylic        acid liquid composition, and if the purity is less than about 99        wt % acrylic acid, repeating said cooling, partially melting,        decanting, and fully melting steps on the purified acrylic acid        liquid composition until a purity of about 99 wt % acrylic acid        is achieved and said glacial acrylic acid composition is        produced.

Additional features of the invention may become apparent to thoseskilled in the art from a review of the following detailed description,taken in conjunction with the examples and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION I Definitions

As used herein, the term “distilled acrylic acid” refers to acomposition of acrylic acid with content of acrylic acid lower thanabout 94 wt %.

As used herein, the term “crude acrylic acid” refers to a composition ofacrylic acid with content of acrylic acid between about 94 wt % andabout 98 wt %.

As used herein, the term “glacial acrylic acid” refers to a compositionof acrylic acid with content of acrylic acid at least about 98 wt %.

As used herein, the term “bio-based” material refers to a renewablematerial.

As used herein, the term “renewable material” refers to a material thatis produced from a renewable resource.

As used herein, the term “renewable resource” refers to a resource thatis produced via a natural process at a rate comparable to its rate ofconsumption (e.g., within a 100 year time frame). The resource can bereplenished naturally, or via agricultural techniques. Non limitingexamples of renewable resources include plants (e.g., sugar cane, beets,corn, potatoes, citrus fruit, woody plants, lignocellulose,hemicellulose, cellulosic waste), animals, fish, bacteria, fungi, andforestry products. These resources can be naturally occurring, hybrids,or genetically engineered organisms. Natural resources, such as crudeoil, coal, natural gas, and peat, which take longer than 100 years toform, are not considered renewable resources. Because at least part ofthe material of the invention is derived from a renewable resource,which can sequester carbon dioxide, use of the material can reduceglobal warming potential and fossil fuel consumption.

As used herein, the term “bio-based content” refers to the amount ofcarbon from a renewable resource in a material as a percent of theweight (mass) of the total organic carbon in the material, as determinedby ASTM D6866-10, Method B.

As used herein, the term “petroleum-based” material refers to a materialthat is produced from fossil material, such as petroleum, natural gas,coal, etc.

As used herein, the term “condensed phosphate” refers to any saltscontaining one or several P—O—P bonds generated by corner sharing of PO₄tetrahedra.

As used herein, the term “cyclophosphate” refers to any cyclic condensedphosphate constituted of two or more corner-sharing PO₄ tetrahedra.

As used herein, the term “monophosphate” or “orthophosphate” refers toany salt whose anionic entity, [PO₄]³⁻, is composed of four oxygen atomsarranged in an almost regular tetrahedral array about a centralphosphorus atom.

As used herein, the term “oligophosphate” refers to any polyphosphatesthat contain five or less PO₄ units.

As used herein, the term “polyphosphate” refers to any condensedphosphates containing linear P—O—P linkages by corner sharing of PO₄tetrahedra leading to the formation of finite chains.

As used herein, the term “ultraphosphate” refers to any condensedphosphate where at least two PO₄ tetrahedra of the anionic entity sharethree of their corners with the adjacent ones.

As used herein, the term “cation” refers to any atom or group ofcovalently-bonded atoms having a positive charge.

As used herein, the term “monovalent cation” refers to any cation with apositive charge of +1.

As used herein, the term “polyvalent cation” refers to any cation with apositive charge equal or greater than +2.

As used herein, the term “anion” refers to any atom or group ofcovalently-bonded atoms having a negative charge.

As used herein, the term “heteropolyanion” refers to any anion withcovalently bonded XO_(p) and YO_(r) polyhedra, and thus includes X—O—Yand possibly X—O—X and Y—O—Y bonds, wherein X and Y represent any atoms,and wherein p and r are any positive integers.

As used herein, the term “heteropolyphosphate” refers to anyheteropolyanion, wherein X represents phosphorus (P) and Y representsany other atom.

As used herein, the term “phosphate adduct” refers to any compound withone or more phosphate anions and one or more non-phosphate anions thatare not covalently linked.

As used herein, the terms “LA” refers to lactic acid, “AA” refers toacrylic acid, “AcH” refers to acetaldehyde, and “PA” refers to propionicacid.

As used herein, the term “particle span” refers to a statisticalrepresentation of a given particle sample and is equal to(D_(v,0.90)−D_(v,0.10))/D_(v,0.50). The term “median particle size” orD_(v,0.50) refers to the diameter of a particle below which 50% of thetotal volume of particles lies. Further, D_(v,0.10) refers to theparticle size that separates the particle sample at the 10% by volumefraction and D_(v,0.90), is the particle size that separates theparticle sample at the 90% by volume fraction.

As used herein, the term “conversion” in % is defined as[hydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof flow rate in (mol/min)−hydroxypropionic acid, hydroxypropionicacid derivatives, or mixtures thereof flow rate out(mol/min)]/[hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof flow rate in (mol/min)]*100. For the purposes of thisinvention, the term “conversion” means molar conversion, unlessotherwise noted.

As used herein, the term “yield” in % is defined as [product flow rateout (mol/min)/hydroxypropionic acid, hydroxypropionic acid derivatives,or mixtures thereof flow rate in (mol/min)]*100. For the purposes ofthis invention, the term “yield” means molar yield, unless otherwisenoted.

As used herein, the term “selectivity” in % is defined as[Yield/Conversion]*100. For the purposes of this invention, the term“selectivity” means molar selectivity, unless otherwise noted.

As used herein, the term “total flow rate out” in mol/min and forhydroxypropionic acid is defined as: (2/3)*[C2 flow rate out(mol/min)]+[C3 flow rate out (mol/min)]+(2/3)*[acetaldehyde flow rateout (mol/min)]+(4/3)*[C4 flow rate out (mol/min)]+[hydroxypropionic acidflow rate out (mol/min)]+[pyruvic acid flow rate out(mol/min)]+(2/3)*[acetic acid flow rate out (mol/min)]+[1,2-propanediolflow rate out (mol/min)]+[propionic acid flow rate out(mol/min)]+[acrylic acid flow rate out(mol/min)]+(5/3)*[2,3-pentanedione flow rate out(mol/min)]+(1/3)*[carbon monoxide flow rate out (mol/min)]+(1/3)*[carbondioxide flow rate out (mol/min)]. If a hydroxypropionic acid derivativeis used instead of hydroxypropionic acid, the above formula needs to beadjusted according to the number of carbon atoms in the hydroxypropionicacid derivative.

As used herein, the term “C2” means ethane and ethylene.

As used herein, the term “C3” means propane and propylene.

As used herein, the term “C4” means butane and butenes.

As used herein, the term “total molar balance” or “TMB” in % is definedas [total flow rate out (mol/min)/hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof flow rate in(mol/min)]*100.

As used herein, the term “the acrylic acid yield was corrected for TMB”is defined as [acrylic acid yield/total molar balance]*100, to accountfor slightly higher flows in the reactor.

As used herein, the term “Gas Hourly Space Velocity” or “GHSV” in h⁻¹ isdefined as [Total gas flow rate (mL/min)/catalyst bed volume (mL)]/60.The total gas flow rate is calculated under Standard Temperature andPressure conditions (STP; 0° C. and 1 atm).

As used herein, the term “Liquid Hourly Space Velocity” or “LHSV” in h⁻¹is defined as [Total liquid flow rate (mL/min)/catalyst bed volume(mL)]/60.

II Purification Processes

Unexpectedly it has been found that, some or all of the processes ofextraction, drying, distilling, cooling, partial melting, and decantingcan be used to produce crude and glacial acrylic acid produced frombio-based acrylic acid. Although the impurities that are present inbio-based acrylic acid are different than those present inpetroleum-based acrylic acid, the same processes that are used to purifythe petroleum-based acrylic acid can be used to purify bio-based acrylicacid to crude or glacial purity levels.

In one embodiment, a glacial acrylic acid composition is providedcomprising at least about 98 wt % acrylic acid, and wherein a portion ofthe remaining impurities in the glacial acrylic acid composition ishydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof.

In one embodiment, a crude acrylic acid composition is providedcomprising between about 94 wt % and about 98 wt % acrylic acid, andwherein a portion of the remaining impurities in the glacial acrylicacid composition is hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof.

Hydroxypropionic acid can be 3-hydroxypropionic acid, 2-hydroxypropionicacid (also called, lactic acid), 2-methyl hydroxypropionic acid, ormixtures thereof. Derivatives of hydroxypropionic acid can be metal orammonium salts of hydroxypropionic acid, alkyl esters ofhydroxypropionic acid, alkyl esters of 2-methyl hydroxypropionic acid,cyclic di-esters of hydroxypropionic acid, hydroxypropionic acidanhydride, or a mixture thereof. Non-limiting examples of metal salts ofhydroxypropionic acid are sodium hydroxypropionate, potassiumhydroxypropionate, and calcium hydroxypropionate. Non-limiting examplesof alkyl esters of hydroxypropionic acid are methyl hydroxypropionate,ethyl hydroxypropionate, butyl hydroxypropionate, 2-ethylhexylhydroxypropionate, or mixtures thereof. A non-limiting example of cyclicdi-esters of hydroxypropionic acid is dilactide.

In one embodiment, the hydroxypropionic acid is lactic acid or 2-methyllactic acid. In another embodiment, the hydroxypropionic acid is lacticacid. Lactic acid can be L-lactic acid, D-lactic acid, or mixturesthereof. In one embodiment, the hydroxypropionic acid, hydroxypropionicacid derivatives, or mixtures thereof in the impurities in the glacialacrylic acid composition are lactic acid, lactic acid derivatives, ormixtures thereof. In another embodiment, the hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof in the impuritiesin the crude acrylic acid composition are lactic acid, lactic acidderivatives, or mixtures thereof.

In one embodiment, the concentration of the hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof in the remainingimpurities of the glacial acrylic acid composition is less than about 2wt %, based on the total amount of the glacial acrylic acid composition.In another embodiment, the hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof in the remaining impurities of theglacial acrylic acid composition is less than about 1 wt %, based on thetotal amount of the glacial acrylic acid composition. In anotherembodiment, the hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof in the remaining impurities of theglacial acrylic acid composition is less than about 400 ppm, based onthe total amount of the glacial acrylic acid composition.

In one embodiment, the bio-based content of the glacial acrylic acid isgreater than about 3%. In another embodiment, the bio-based content ofthe glacial acrylic acid is greater than 30%. In yet another embodiment,the bio-based content of the glacial acrylic acid is greater than about90%. In one embodiment, the bio-based content of the crude acrylic acidis greater than about 3%. In another embodiment, the bio-based contentof the crude acrylic acid is greater than 30%. In yet anotherembodiment, the bio-based content of the crude acrylic acid is greaterthan about 90%.

The glacial or crude acrylic acid composition can be made from anaqueous solution of acrylic acid produced from renewable resources ormaterials and fed into the purification process to produce crude acrylicacid or glacial acrylic acid. Non-limiting examples of renewableresources or materials for the production of the aqueous solution ofacrylic acid are hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof; glycerin; carbon monoxide and ethyleneoxide; carbon dioxide and ethylene; and crotonic acid. In oneembodiment, the renewable resources or materials are hydroxypropionicacid, hydroxypropionic acid derivatives, or mixtures thereof. In anotherembodiment, the renewable resources or materials are lactic acid, lacticacid derivatives, or mixtures thereof. In yet another embodiment, therenewable resource or material is lactic acid.

In one embodiment, the aqueous solution of acrylic acid comprises: 1)acrylic acid; 2) lactic acid, lactic acid derivatives, or mixturesthereof, and is essentially free of maleic anhydride, furfural, andformic acid. In another embodiment, the aqueous solution of acrylic acidhas from about 4 wt % to about 80 wt % acrylic acid. In anotherembodiment, the aqueous solution of acrylic acid has from about 4 wt %to about 40 wt % acrylic acid. In yet another embodiment, the aqueoussolution of acrylic acid has from about 5 wt % to about 25 wt % acrylicacid. In another embodiment, the aqueous solution of acrylic acid hasfrom about 8 wt % to about 16 wt % acrylic acid.

In one embodiment, the aqueous solution of acrylic acid has from about0.001 wt % to about 50 wt % lactic acid, lactic acid derivatives, ormixtures thereof. In another embodiment, the aqueous solution of acrylicacid has from about 0.001 wt % to about 20 wt % % lactic acid, lacticacid derivatives, or mixtures thereof. In yet another embodiment, theaqueous solution of acrylic acid has about 6 wt % % lactic acid, lacticacid derivatives, or mixtures thereof.

In one embodiment, the aqueous solution of acrylic acid has from about 8wt % to about 16 wt % acrylic acid and from about 0.1 wt % to about 10wt % lactic acid, lactic acid derivatives, or mixtures thereof, andwherein said aqueous solution of acrylic acid is essentially free ofmaleic anhydride, furfural, and formic acid. Non-limiting examples ofimpurities that can be present in the aqueous solution of acrylic acidare acetaldehyde, acetic acid, and propanoic acid.

The aqueous solution of acrylic acid can be extracted with a solvent toproduce an extract. In one embodiment, the solvent is selected from thegroup consisting of ethyl acetate, isobutyl acetate, methyl acetate,toluene, dimethyl phthalate, hexane, pentane, diphenyl ether, ethylhexanoic acid, N-methylpyrrolidone, C6 to C10 paraffin fractions, andmixtures thereof. In another embodiment, the extraction solvent is ethylacetate. In one embodiment, the extraction solvent can form an azeotropewith water.

In one embodiment, the solvent comprises at least one polymerizationinhibitor. Non-limiting examples of polymerization inhibitors arephenothiazine and 4-methoxy phenol. In another embodiment, the glacialacrylic acid comprises from about 200 ppm to about 400 ppm4-methoxyphenol. In another embodiment, the polymerization inhibitor isadded to the aqueous solution of acrylic acid before the extractingstep.

After the extraction, the extract can be dried to produce a driedextract. The drying can be achieved with a variety of methods, such as,and not by way of limitation, distillation and sorption. In oneembodiment, the drying is performed by azeotropic distillation. Inanother embodiment, the sorption is performed on a solid powder. In yetanother embodiment, the solid powder is selected from the groupconsisting of magnesium sulfate, sodium sulfate, calcium sulfate,molecular sieves, metal hydrides, reactive metals, and mixtures thereof.In yet another embodiment, the sorption is performed with sodium sulfateand is followed by filtration to produce a dried filtrate.

The dried extract or dried filtrate can be further processed bydistillation to produce a distilled acrylic acid composition. In oneembodiment, the distillation is vacuum distillation at about 70 mm Hgand about 40° C. to produce a distilled crude acrylic acid composition,and is followed by a fractional distillation at about 40 mm Hg andcollecting fractions from 59° C. to 62° C. to produce the distilledacrylic acid composition.

In one embodiment, cooling of the distilled acrylic acid composition toa temperature from about −21° C. to about 14° C. produces crystals ofacrylic acid; partially melting the crystals of acrylic acid produces aliquid/solid mixture; decanting the liquid/solid mixture produces apurified acrylic acid solid composition; fully melting the purifiedacrylic acid solid composition produces a purified acrylic acid liquidcomposition; and determining acrylic acid purity of the purified acrylicacid liquid composition, and if the purity is less than about 98 wt %acrylic acid, repeating said cooling, partially melting, decanting, andfully melting steps on the purified acrylic acid liquid compositionuntil a purity of about 98 wt % acrylic acid is achieved and a glacialacrylic acid composition is produced.

In another embodiment, cooling of the distilled acrylic acid compositionto a temperature from about −21° C. to about 14° C. produces crystals ofacrylic acid; partially melting the crystals of acrylic acid produces aliquid/solid mixture; decanting the liquid/solid mixture produces apurified acrylic acid solid composition; fully melting the purifiedacrylic acid solid composition produces a purified acrylic acid liquidcomposition; and determining acrylic acid purity of the purified acrylicacid liquid composition, and if the purity is less than about 94 wt %acrylic acid, repeating said cooling, partially melting, decanting, andfully melting steps on the purified acrylic acid liquid compositionuntil a purity of about 94 wt % acrylic acid is achieved and a crudeacrylic acid composition is produced.

In yet another embodiment, cooling of the distilled acrylic acidcomposition to a temperature from about −21° C. to about 14° C. producescrystals of acrylic acid; partially melting the crystals of acrylic acidproduces a liquid/solid mixture; decanting the liquid/solid mixtureproduces a purified acrylic acid solid composition; fully melting thepurified acrylic acid solid composition produces a purified acrylic acidliquid composition; and determining acrylic acid purity of the purifiedacrylic acid liquid composition, and if the purity is less than about 99wt % acrylic acid, repeating said cooling, partially melting, decanting,and fully melting steps on the purified acrylic acid liquid compositionuntil a purity of about 99 wt % acrylic acid is achieved and a glacialacrylic acid composition is produced.

In one embodiment, the distilling step is followed by determining theacrylic acid purity of the distilled acrylic acid composition, and ifthe purity is less than about 98 wt % acrylic acid, repeating saiddistilling step on the purified acrylic acid composition until a purityof about 98 wt % acrylic acid is achieved and a glacial acrylic acidcomposition is produced. In another embodiment, the distilling step isfollowed by determining the acrylic acid purity of the distilled acrylicacid composition, and if the purity is less than about 94 wt % acrylicacid, repeating said distilling step on the purified acrylic acidcomposition until a purity of about 94 wt % acrylic acid is achieved anda crude acrylic acid composition is produced.

In one embodiment, the distilled acrylic acid composition is cooled to atemperature from about 0° C. to about 5° C. to produce crystals ofacrylic acid.

In one embodiment of the present invention, the glacial acrylic acidcomposition is produced by the steps comprising: a) providing an aqueoussolution of acrylic acid comprising 1) acrylic acid and 2) lactic acid,lactic acid derivatives, or mixtures thereof, and wherein said aqueoussolution of acrylic acid is essentially free of maleic anhydride,furfural, and formic acid; b) extracting said aqueous solution ofacrylic acid with a solvent to produce an extract; c) drying saidextract to produce a dried extract; d) distilling said dried extract toproduce crude acrylic acid; e) cooling said crude acrylic acid to atemperature from about −21° C. to about 14° C. to produce crystals ofacrylic acid; f) partially melting said crystals of acrylic acid toproduce a liquid/solid mixture; g) decanting said liquid/solid mixtureto produce a acrylic acid solid composition; h) fully melting saidpurified acrylic acid solid composition to produce a purified acrylicacid composition; and i) determining the acrylic acid purity of saidpurified acrylic acid liquid composition and if the purity is less than98 wt % acrylic acid repeating said cooling, partially melting,decanting, and fully melting steps on the purified acrylic acid liquidcomposition until a purity of about 98 wt % is achieved to produceglacial acrylic acid composition.

In another embodiment of the present invention, a glacial acrylic acidcomposition is provided produced by the steps comprising: a) providingan aqueous solution of acrylic acid comprising: 1) acrylic acid; and 2)lactic acid, lactic acid derivatives, or mixtures thereof, and whereinsaid aqueous solution of acrylic acid is essentially free of maleicanhydride, furfural, and formic acid; b) extracting said aqueoussolution of acrylic acid with a solvent to produce an extract; c) dryingsaid extract to produce a dried extract; d) distilling said driedextract to produce a distilled acrylic acid composition; and e)determining the acrylic acid purity of said distilled acrylic acidcomposition, and if the purity is less than about 98 wt % acrylic acid,repeating said distilling step on the purified acrylic acid compositionuntil a purity of about 98 wt % acrylic acid is achieved and saidglacial acrylic acid composition is produced.

In one embodiment of the present invention, a crude acrylic acidcomposition is provided produced by the steps comprising: a) providingan aqueous solution of acrylic acid comprising: 1) acrylic acid; and 2)lactic acid, lactic acid derivatives, or mixtures thereof, and whereinsaid aqueous solution of acrylic acid is essentially free of maleicanhydride, furfural, and formic acid; b) extracting said aqueoussolution of acrylic acid with a solvent to produce an extract; c) dryingsaid extract to produce a dried extract; d) distilling said driedextract to produce a distilled acrylic acid composition; and e)determining the acrylic acid purity of said distilled acrylic acidcomposition, and if the purity is less than about 94 wt % acrylic acid,repeating said distilling step on the purified acrylic acid compositionuntil a purity of about 94 wt % acrylic acid is achieved and said crudeacrylic acid composition is produced.

In another embodiment of the present invention, a crude acrylic acidcomposition is provided produced by the steps comprising: a) providingan aqueous solution of acrylic acid comprising: 1) acrylic acid; and 2)lactic acid, lactic acid derivatives, or mixtures thereof, and whereinsaid aqueous solution of acrylic acid is essentially free of maleicanhydride, furfural, and formic acid; b) extracting said aqueoussolution of acrylic acid with a solvent to produce an extract; c) dryingsaid extract to produce a dried extract; d) distilling said driedextract to produce a distilled acrylic acid composition; e) cooling saiddistilled acrylic acid composition to a temperature from about −21° C.to about 14° C. to produce crystals of acrylic acid; f) partiallymelting said crystals of acrylic acid to produce a liquid/solid mixture;g) decanting said liquid/solid mixture to produce a purified acrylicacid solid composition; h) fully melting said purified acrylic acidsolid composition to produce a purified acrylic acid liquid composition;and i) determining the acrylic acid purity of said purified acrylic acidliquid composition, and if the purity is less than about 94 wt % acrylicacid, repeating said cooling, partially melting, decanting, and fullymelting steps on the purified acrylic acid liquid composition until apurity of about 94 wt % acrylic acid is achieved and said crude acrylicacid composition is produced.

In one embodiment of the present invention, a glacial acrylic acidcomposition is provided comprising about 99 wt % acrylic acid, producedby the steps comprising: a) providing an aqueous solution of acrylicacid comprising: 1) from about 8 wt % to about 16 wt % acrylic acid; and2) from about 0.1 wt % to about 10 wt % lactic acid, lactic acidderivatives, or mixtures thereof, and wherein said aqueous solution ofacrylic acid is essentially free of maleic anhydride, furfural, andformic acid; b) extracting said aqueous solution of acrylic acid, withethyl acetate to produce an extract; c) drying said extract with sodiumsulfate to produce a dried extract; d) vacuum distilling said driedextract at about 70 mm Hg and 40° C. to produce a distilled crudeacrylic acid composition; e) fractionally distilling said distilledcrude acrylic acid composition at about 40 mm Hg and collectingfractions from 59° C. to 62° C. to produce a distilled acrylic acidcomposition; f) cooling said distilled acrylic acid composition to atemperature from about 0° C. to about 5° C. to produce crystals ofacrylic acid; g) partially melting said crystals of acrylic acid toproduce a liquid/solid mixture; h) decanting said liquid/solid mixtureto produce a purified acrylic acid solid composition; i) fully meltingsaid purified acrylic acid composition to produce a purified acrylicacid liquid composition; and j) determining the acrylic acid purity ofsaid purified acrylic acid liquid composition, and if the purity is lessthan about 99 wt % acrylic acid, repeating said cooling, partiallymelting, decanting, and fully melting steps on the purified acrylic acidliquid composition until a purity of about 99 wt % acrylic acid isachieved and said glacial acrylic acid composition is produced.

III Catalysts for the Conversion of Hydroxypropionic Acid or ItsDerivatives to Acrylic Acid or Its Derivatives

In one embodiment, the catalyst comprises: (a) at least one condensedphosphate anion selected from the group consisting of formulae (I),(II), and (III),

[P_(n)O_(3n+1)]^((n+2)−)  (I)

[P_(n)O_(3n)]^(n−)  (II)

[P_((2m+n))O_((5m+3n))]^(n−)  (III)

wherein n is at least 2 and m is at least 1, and (b) at least twodifferent cations, wherein the catalyst is essentially neutrallycharged, and further, wherein the molar ratio of phosphorus to the atleast two different cations is between about 0.7 and about 1.7.

The anions defined by formulae (I), (II), and (III) are also referred toas polyphosphates (or oligophosphates), cyclophosphates, andultraphosphates, respectively.

In another embodiment, the catalyst comprises: (a) at least onecondensed phosphate anion selected from the group consisting of formulae(I) and (II),

[P_(n)O_(3n+1)]^((n+2)−)  (I)

[P_(n)O_(3n)]^(n−)  (II)

wherein n is at least 2, and (b) at least two different cations, whereinthe catalyst is essentially neutrally charged, and further, wherein themolar ratio of phosphorus to the at least two different cations isbetween about 0.7 and about 1.7.

The cations can be monovalent or polyvalent. In one embodiment, onecation is monovalent and the other cation is polyvalent. In anotherembodiment, the polyvalent cation is selected from the group consistingof divalent cations, trivalent cations, tetravalent cations, pentavalentcations, and mixtures thereof. Non-limiting examples of monovalentcations are H⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Rb⁺, Tl⁺, and mixturesthereof. In one embodiment, the monovalent cation is selected from thegroup consisting of Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, and mixtures thereof; inanother embodiment, the monovalent cation is Na⁺ or K⁺; and in yetanother embodiment, the monovalent cation is K⁺. Non-limiting examplesof polyvalent cations are cations of the alkaline earth metals (i.e.,Be, Mg, Ca, Sr, Ba, and Ra), transition metals (e.g. Y, Ti, Zr, V, Nb,Cr, Mo, Mn, Re, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu, Ag, and Au), poor metals(e.g. Zn, Ga, Si, Ge, B, Al, In, Sb, Sn, Bi, and Pb), lanthanides (e.g.La and Ce), and actinides (e.g. Ac and Th). In one embodiment, thepolyvalent cation is selected from the group consisting of Be²⁺, Mg²⁺,Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Sn²⁺, Pb²⁺,Ti³⁺, Cr³⁺, Mn³⁺, Fe³⁺, Al³⁺, Ga³⁺, Y³⁺, In³⁺, Sb³⁺, Bi³⁺, Si⁴⁺, Ti⁴⁺,V⁴⁺, Ge⁴⁺, Mo⁴⁺, Pt⁴⁺, V⁵⁺, Nb⁵⁺, Sb⁵⁺, and mixtures thereof. In oneembodiment, the polyvalent cation is selected from the group consistingof Ca²⁺, Ba²⁺, Cu²⁺, Mn²⁺, Mn³⁺, and mixtures thereof; in anotherembodiment, the polyvalent cation is selected from the group consistingof Ca²⁺, Ba²⁺, Mn³⁺, and mixtures thereof; and in yet anotherembodiment, the polyvalent cation is Ba²⁺.

The catalyst can include cations: (a) H⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, ormixtures thereof; and (b) Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Fe²⁺,Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Sn²⁺, Pb²⁺, Ti³⁺, Cr³⁺, Mn³⁺, Fe³⁺, Al³⁺,Ga³⁺, Y³⁺, In³⁺, Sb³⁺, Bi³⁺, Si⁴⁺, Ti⁴⁺, V⁴⁺, Ge⁴⁺, Mo⁴⁺, Pt⁴⁺, V⁵⁺,Nb⁵⁺, Sb⁵⁺, or mixtures thereof. In one embodiment the catalystcomprises Li⁺, Na⁺, or K⁺ as monovalent cation, and Ca²⁺, Ba²⁺, or Mn³⁺as polyvalent cation; in another embodiment, the catalyst comprises Na⁺or K⁺ as monovalent cation, and Ca²⁺ or Ba²⁺ as polyvalent cation; andin yet another embodiment, the catalyst comprises K⁺ as the monovalentcation and Ba²⁺ as the polyvalent cation.

In one embodiment, the catalyst comprises Ba_(2-x-s)K_(2x)H_(2s)P₂O₇ and(KPO₃)_(n), wherein x and s are greater or equal to 0 and less thanabout 0.5 and n is a positive integer. In another embodiment, thecatalyst comprises Ca_(2-x-s)K_(2x)H_(2x)P₂O₇ and (KPO₃)_(n), wherein xand s are greater or equal to 0 and less than about 0.5 and n is apositive integer. In yet another embodiment, the catalyst comprisesMn_(1-x-s)K_(1+3x)H_(3s)P₂O₇ or Mn_(1-x-s)K_(2+2x)H_(2s)P₂O₇ and(KPO₃)_(n) wherein x and s are greater or equal to 0 and less than about0.5 and n is a positive integer. In another embodiment, the catalystcomprises any blend of Ba_(2-x-s)K_(2x)H_(2s)P₂O₇,Ca_(2-x-s)K_(2x)H_(2s)P₂O₇, Mn_(1-x-s)K_(1+3x)H_(3s)P₂O₇ orMn_(1-x-s)K_(2+2x)H_(2s)P₂O₇; and (KPO₃)_(n), wherein x and s aregreater or equal to 0 and less than about 0.5 and n is a positiveinteger.

In one embodiment, the molar ratio of phosphorus to the cations in thecatalyst is between about 0.7 and about 1.7; in another embodiment, themolar ratio of phosphorus to the cations in the catalyst is betweenabout 0.8 and about 1.3; and in yet another embodiment, the molar ratioof phosphorus to the cations in the catalyst is about 1.

In one embodiment, the catalyst comprises: (a) at least two differentcondensed phosphate anions selected from the group consisting offormulae (I), (II), and (III),

[P_(n)O_(3n+1)]^((n+2)−)  (I)

[P_(n)O_(3n)]^(n−)  (II)

[P_((2m+n))O_((5m+3n))]^(n−)  (III)

wherein n is at least 2 and m is at least 1, and (b) one cation, whereinthe catalyst is essentially neutrally charged, and further, wherein themolar ratio of phosphorus to the cation is between about 0.5 and about4.0. In another embodiment, the molar ratio of phosphorus to the cationis between about t/2 and about t, wherein t is the charge of the cation.

The catalyst can include an inert support that is constructed of amaterial comprising silicates, aluminates, carbons, metal oxides, andmixtures thereof. Alternatively, the carrier is inert relative to thereaction mixture expected to contact the catalyst. In the context of thereactions expressly described herein, in one embodiment the carrier is alow surface area silica or zirconia. When present, the carrierrepresents an amount of about 5 wt % to about 98 wt %, based on thetotal weight of the catalyst. Generally, a catalyst that includes aninert support can be made by one of two exemplary methods: impregnationor co-precipitation. In the impregnation method, a suspension of thesolid inert support is treated with a solution of a pre-catalyst, andthe resulting material is then activated under conditions that willconvert the pre-catalyst to a more active state. In the co-precipitationmethod, a homogenous solution of the catalyst ingredients isprecipitated by the addition of additional ingredients.

In another embodiment, the catalyst can be sulfate salts; phosphatesalts; mixtures of sulfate and phosphate salts; bases; zeolites ormodified zeolites; metal oxides or modified metal oxides; supercriticalwater, or mixtures thereof.

IV Catalyst Preparation Methods

In one embodiment, the method of preparing the catalyst includes mixingand heating at least two different phosphorus containing compounds,wherein each said compound is described by one of the formulae (IV) to(XXV), or any of the hydrated forms of said formulae:

M¹ _(y)(H_(3−y)PO₄)  (IV)

M^(II) _(y)(H_(3−y)PO₄)₂  (V)

M^(III) _(y)(H_(3−y)PO₄)₃  (VI)

M^(IV) _(y)(H_(3−y)PO₄)₄  (VII)

(NH₄)_(y)(H_(3−y)PO₄)  (VIII)

M^(II) _(a)(OH)_(b)(PO₄)_(c)  (IX)

M^(III) _(d)(OH)_(e)(PO₄)_(f)  (X)

M^(II)M^(I)PO₄  (XI)

M^(III)M^(I) ₃(PO₄)₂  (XII)

M^(IV) ₂M^(I)(PO₄)₃  (XIII)

M^(I) _(z)H_(4−z)P₂O₇  (XIV)

M^(II) _(v)H_((4−2v))P₂O₇  (XV)

M^(IV)P₂O₇  (XVI)

(NH₄)_(z)H_(4−z)P₂O₇  (XVII)

M^(III)M^(I)P₂O₇  (XVIII)

M^(I)H_(w)(PO₃)_((1+w))  (XIX)

M^(II)H_(w)(PO₃)_((2+w))  (XX)

M^(III)H_(w)(PO₃)_((3+w))  (XXI)

M^(IV)H_(w)(PO₃)_((4+w))  (XXII)

M^(II) _(g)M^(I) _(h)(PO₃)_(i)  (XXIII)

M^(III) _(j)M^(I) _(k)(PO₃)_(l)  (XXIV)

P₂O₅  (XXV)

wherein M^(I) is a monovalent cation; wherein M^(II) is a divalentcation; wherein M^(III) is a trivalent cation; wherein M^(IV) is atetravalent cation; wherein y is 0, 1, 2, or 3; wherein z is 0, 1, 2, 3,or 4; wherein v is 0, 1, or 2; wherein w is 0 or any positive integer;and wherein a, b, c, d, e, f, g, h, i, j, k, and l are any positiveintegers, such that the equations: 2a=b+3c, 3d=e+3f, i=2g+h, and l=3j+kare satisfied.

In one embodiment, the catalyst is prepared by mixing and heating one ormore phosphorus containing compounds of formula (IV), wherein y is equalto 1, and one or more phosphorus containing compounds of formula (V),wherein y is equal to 2. In another embodiment, the catalyst is preparedby mixing and heating M^(I)H₂PO₄ and M^(II)HPO₄. In one embodiment,M^(I) is K⁺ and M^(II) is Ca²⁺, i.e., the catalyst is prepared by mixingand heating KH₂PO₄ and CaHPO₄; or M^(I) is K and M^(II) is Ba²⁺, i.e.,the catalyst is prepared by mixing and heating KH₂PO₄ and BaHPO₄.

In one embodiment, the catalyst is prepared by mixing and heating one ormore phosphorus containing compound of formula (IV), wherein y is equalto 1, one or more phosphorus containing compounds of formula (XV),wherein v is equal to 2. In another embodiment, the catalyst is preparedby mixing and heating M^(I)H₂PO₄ and M^(II) ₂P₂O₇. In one embodiment,M^(I) is K⁺ and M^(II) is Ca²⁺, i.e., the catalyst is prepared by mixingand heating KH₂PO₄ and Ca₂P₂O₇; or M^(I) is K⁺ and M^(II) is Ba²⁺, i.e.,the catalyst is prepared by mixing and heating KH₂PO₄ and Ba₂P₂O₇.

In another embodiment, the molar ratio of phosphorus to the cations inthe catalyst is between about 0.7 and about 1.7; in yet anotherembodiment, the molar ratio of phosphorus to the cations in the catalystis between about 0.8 and about 1.3; and in another embodiment, the molarratio of phosphorus to the cations in the catalyst is about 1.

In another embodiment, the method of preparing the catalyst includesmixing and heating (a) at least one phosphorus containing compound,wherein each said compound is described by one of the formulae (IV) to(XXV), or any of the hydrated forms of said formulae:

M^(I) _(y)(H_(3−y)PO₄)  (IV)

M^(II) _(y)(H_(3−y)PO₄)₂  (V)

M^(III) _(y)(H_(3−y)PO₄)₃  (VI)

M^(IV) _(y)(H_(3−y)PO₄)₄  (VII)

(NH₄)_(y)(H_(3−y)PO₄)  (VIII)

M^(II) _(a)(OH)_(b)(PO₄)_(c)  (IX)

M^(III) _(d)(OH)_(e)(PO₄)_(f)  (X)

M^(II)M^(I)PO₄  (XI)

M^(III)M^(I) ₃(PO₄)₂  (XII)

M^(IV) ₂M^(I)(PO₄)₃  (XIII)

M^(I) _(z)H_(4−z)P₂O₇  (XIV)

M^(II) _(v)H_((4−2v))P₂O₇  (XV)

M^(IV)P₂O₇  (XVI)

(NH₄)_(z)H_(4−z)P₂O₇  (XVII)

M^(III)M^(I)P₂O₇  (XVIII)

M^(I)H_(w)(PO₃)_((1+w))  (XIX)

M^(II)H_(w)(PO₃)_((2+w))  (XX)

M^(III)H_(w)(PO₃)_((3+w))  (XXI)

M^(IV)H_(w)(PO₃)_((4+w))  (XXII)

M^(II) _(g)M^(I) _(h)(PO₃)_(i)  (XXIII)

M^(III) _(j)M^(I) _(k)(PO₃)_(l)  (XXIV)

P₂O₅  (XXV)

wherein y is 0, 1, 2, or 3; wherein z is 0, 1, 2, 3, or 4; wherein v is0, 1, or 2; wherein w is 0 or any positive integer; and wherein a, b, c,d, e, f, g, h, i, j, k, and l are any positive integers, such that theequations: 2a=b+3c, 3d=e+3f, i=2g+h, and l=3j+k are satisfied, and (b)at least one non-phosphorus containing compound selected from the groupconsisting of nitrate salts, carbonate salts, acetate salts, metaloxides, chloride salts, sulfate salts, and metal hydroxides, whereineach said compound is described by one of the formulae (XXVI) to (XL),or any of the hydrated forms of said formulae:

M^(I)NO₃  (XXVI)

M^(II)(NO₃)₂  (XXVII)

M^(III)(NO₃)₃  (XXVIII)

M^(I) ₂CO₃  (XXIX)

M^(II)CO₃  (XXX)

M^(III) ₂(CO₃)₃  (XXXI)

(CH₃COO)M^(I)  (XXXII)

(CH₃COO)₂M^(II)  (XXXIII)

(CH₃COO)₃M^(III)  (XXXIV)

(CH₃COO)₄M^(IV)  (XXXV)

M^(I) ₂O  (XXXVI)

M^(II)O  (XXXVII)

M^(III) ₂O₃  (XXXVIII)

M^(IV)CO₂  (XXXIX)

M^(I)Cl  (XXXX)

M^(II)Cl₂  (XXXXI)

M^(III)Cl₃  (XXXXII)

M^(IV)Cl₄  (XXXXIII)

M^(I) ₂SO₄  (XXXXIV)

M^(II)SO₄  (XXXXV)

M^(III) ₂(SO₄)₃  (XXXXVI)

M^(IV)(SO₄)₂  (XXXXVII)

M^(I)OH  (XXXVIII)

M^(II)(OH)₂  (XXXIX)

M^(III))OH)₃  (XL).

In another embodiment, the non-phosphorus containing compounds can beselected from the group consisting of carboxylic acid-derived salts,halide salts, metal acetylacetonates, and metal alkoxides.

In one embodiment of the present invention, the molar ratio ofphosphorus to the cations in the catalyst is between about 0.7 and about1.7; in another embodiment, the molar ratio of phosphorus to the cationsin the catalyst is between about 0.8 and about 1.3; and in yet anotherembodiment, the molar ratio of phosphorus to the cations in the catalystis about 1.

In another embodiment of the present invention, the catalyst is preparedby mixing and heating one or more phosphorus containing compounds offormulae (IV) to (XXV) or their hydrated forms, and one or more nitratesalts of formulae (XXVI) to (XXVIII) or their hydrated forms. In anotherembodiment of the present invention, the catalyst is prepared by mixingand heating one or more phosphorus containing compounds of formula (IV)and one or more nitrate salts of formula (XXVII). In a furtherembodiment of the present invention, the catalyst is prepared by mixingand heating a phosphorus containing compound of formula (IV) wherein yis equal to 2, a phosphorus containing compound of formula (IV) whereiny is equal to 0 (i.e., phosphoric acid), and a nitrate salt of formula(XXVII). In yet another embodiment of the present invention, thecatalyst is prepared by mixing and heating K₂HPO₄, H₃PO₄, and Ba(NO₃)₂.In yet another embodiment, the catalyst is prepared by mixing andheating K₂HPO₄, H₃PO₄, and Ca(NO₃)₂.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds offormula (IV) and one or more nitrate salts of formula (XXVIII). In afurther embodiment of the present invention, the catalyst is prepared bymixing and heating a phosphorus containing compound of formula (IV)wherein y is equal to 2, a phosphorus containing compound of formula(IV) wherein y is equal to 0 (i.e., phosphoric acid), and a nitrate saltof formula (XXVIII). In yet another embodiment of the present invention,the catalyst is prepared by mixing and heating K₂HPO₄, H₃PO₄, andMn(NO₃)₂.4H₂O.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds offormula (V) and one or more nitrate salts of formula (XXVI). In anotherembodiment of the present invention, the catalyst is prepared by mixingand heating a phosphorus containing compound of formula (V) wherein y isequal to 2, a phosphorus containing compound of formula (V) wherein y isequal to 0 (i.e., phosphoric acid), and a nitrate salt of formula(XXVI). In yet another embodiment of the present invention, the catalystis prepared by mixing and heating BaHPO4, H₃PO₄, and KNO₃. In anotherembodiment, the catalyst is prepared by mixing and heating CaHPO₄,H₃PO₄, and KNO₃.

In one embodiment of this invention, the catalyst is prepared by mixingand heating one or more phosphorus containing compounds of formula (V),one or more phosphorus containing compounds of formula (XV), and one ormore nitrate salts of formula (XXVI). In a further embodiment of thisinvention, the catalyst is prepared by mixing and heating a phosphoruscontaining compound of formula (V), wherein y is equal to 0 (i.e.,phosphoric acid); a phosphorus containing compound of formula (XV),wherein v is equal to 2; and a nitrate salt of formula (XXVI). Inanother embodiment of the present invention, the catalyst is prepared bymixing and heating H₃PO₄, Ca₂P₂O₇, and KNO₃. In yet another embodiment,the catalyst is prepared by mixing and heating H₃PO₄, Ba₂P₂O₇, and KNO₃.

In another embodiment of this invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds offormula (VI) and one or more nitrate salts of formula (XXVI). In anotherembodiment of this invention, the catalyst is prepared by mixing andheating a phosphorus containing compound of formula (VI), wherein y isequal to 3; a phosphorus containing compound of formula (VI), wherein yis equal to 0 (i.e., phosphoric acid); and a nitrate salt of formula(XXVI). In yet another embodiment of this invention, the catalyst isprepared by mixing and heating MnPO₄.qH₂O, H₃PO₄, and KNO₃.

In one embodiment of this invention, the catalyst is prepared by mixingand heating one or more phosphorus containing compounds of formula (IV),one or more phosphorus containing compounds of formula (IX), and one ormore nitrate salts of formula (XXVII). In another embodiment of thisinvention, the catalyst is prepared by mixing and heating a phosphoruscontaining compound of formula (IV), wherein y is equal to 2; aphosphorus containing compound of formula (IV), wherein y is equal to 0(i.e., phosphoric acid); a phosphorus containing compound of formula(IX), wherein a is equal to 2, b is equal to 1, and c is equal to 1; anda nitrate salt of formula (XXVII). In yet another embodiment of thisinvention, the catalyst is prepared by mixing and heating K₂HPO₄, H₃PO₄,Cu₂(OH)PO₄, and Ba(NO₃)₂.

In one embodiment of this invention, the catalyst is prepared by mixingand heating one or more phosphorus containing compounds of formula (V),one or more phosphorus containing compounds of formula (IX), and one ormore nitrate salts of formula (XXVI). In another embodiment of thisinvention, the catalyst is prepared by mixing and heating a phosphoruscontaining compound of formula (V), wherein y is equal to 3; aphosphorus containing compound of formula (V), wherein y is equal to 0(i.e., phosphoric acid); a phosphorus containing compound of formula(IX), wherein a is equal to 2, b is equal to 1, and c is equal to 1; anda nitrate salt of formula (XXVI). In yet another embodiment, thecatalyst is prepared by mixing and heating Ba₃(PO₄)₂, H₃PO₄, Cu₂(OH)PO₄,and KNO₃.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds describedby one of the formulae (IV) to (XXV) or any of the hydrated forms, andone or more carbonate salts described by one of the formulae (XXIX) to(XXXI) or any of the hydrated forms.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds describedby one of the formulae (IV) to (XXV) or any of the hydrated forms, andone or more acetate salts described by one of the formulae (XXXII) to(XXXV), any other organic acid-derived salts, or any of the hydratedforms.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds describedby one of the formulae (IV) to (XXV) or any of the hydrated forms, andone or more metal oxides described by one of the formulae (XXXVI) to(XXXIX) or any of the hydrated forms.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds describedby one of the formulae (IV) to (XXV) or any of the hydrated forms, andone or more chloride salts described by one of the formulae (XXXX) to(XXXXIII), any other halide salts, or any of the hydrated forms.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds describedby one of the formulae (IV) to (XXV) or any of the hydrated forms, andone or more sulfate salts described by one of the formulae (XXXXIV) to(XXXXVII) or any of the hydrated forms.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds describedby one of the formulae (IV) to (XXV) or any of the hydrated forms, andone or more hydroxides described by one of the formulae (XXXXVIII) to(XL) or any of the hydrated forms.

In one embodiment of the present invention, the catalyst is prepared bymixing and heating one or more phosphorus containing compounds offormulae (IV) to (XXV), and two or more non-phosphorus containingcompounds of formulae (XXVI) to (XL) or their hydrated forms.

In one embodiment, the molar ratio of phosphorus to the cations (i.e.,M^(I)+M^(II)+M^(III)+ . . . ) is between about 0.7 and about 1.7; inanother embodiment, the molar ratio of phosphorus to the cations (i.e.,M^(I)+M^(II)+M^(III)+ . . . ) is between about 0.8 and about 1.3, and inyet another embodiment, the molar ratio of phosphorus to the cations(i.e., M^(I)+M^(II)+M^(III)+ . . . ) is about 1. For example, in anembodiment when the catalyst includes potassium (K⁺) and barium (Ba²⁺),the molar ratio between phosphorus and the metals (K+Ba) is betweenabout 0.7 and about 1.7; and in another embodiment, the molar ratiobetween phosphorus and the metals (K+Ba) is about 1.

When the catalyst includes only two different cations, the molar ratiobetween cations is, in one embodiment, between about 1:50 and about50:1; and in another embodiment, the molar ratio between cations isbetween about 1:4 and about 4:1. For example, when the catalyst includespotassium (K⁺) and barium (Ba²⁺), the molar ratio between them (K:Ba),in one embodiment, is between about 1:4 and about 4:1. Also, when thecatalyst is prepared by mixing and heating K₂HPO₄, Ba(NO₃)₂, and H₃PO₄,the potassium and barium are present, in another embodiment, in a molarratio, K:Ba, between about 2:3 to about 1:1.

In one embodiment, the catalyst can include an inert support that isconstructed of a material comprising silicates, aluminates, carbons,metal oxides, and mixtures thereof. Alternatively, the carrier is inertrelative to the reaction mixture expected to contact the catalyst. Inanother embodiment, the method of preparing the catalyst can furtherinclude mixing an inert support with the catalyst before, during, orafter the mixing and heating of the phosphorus containing compounds,wherein the inert support includes silicates, aluminates, carbons, metaloxides, and mixtures thereof. In yet another embodiment, the method ofpreparing the catalyst can further include mixing an inert support withthe catalyst before, during, or after the mixing and heating of thephosphorus containing compounds and the non-phosphorus containingcompounds, wherein the inert support includes silicates, aluminates,carbons, metal oxides, and mixtures thereof.

Mixing of the phosphorus containing compounds or the phosphoruscontaining and non-phosphorus containing compounds of the catalyst canbe performed by any method known to those skilled in the art, such as,by way of example and not limitation: solid mixing and co-precipitation.In the solid mixing method, the various components are physically mixedtogether with optional grinding using any method known to those skilledin the art, such as, by way of example and not limitation, shear,extensional, kneading, extrusion, and others. In the co-precipitationmethod, an aqueous solution or suspension of the various components,including one or more of the phosphate compounds, is prepared, followedby optional filtration and heating to remove solvents and volatilematerials (e.g., water, nitric acid, carbon dioxide, ammonia, or aceticacid). The heating is typically done using any method known to thoseskilled in the art, such as, by way of example and not limitation,convection, conduction, radiation, microwave heating, and others.

In one embodiment of the invention, the catalyst is calcined.Calcination is a process that allows chemical reaction and/or thermaldecomposition and/or phase transition and/or removal of volatilematerials. The calcination process is carried out with any equipmentknown to those skilled in the art, such as, by way of example and notlimitation, furnaces or reactors of various designs, including shaftfurnaces, rotary kilns, hearth furnaces, and fluidized bed reactors. Thecalcination temperature is, in one embodiment, about 200° C. to about1200° C.; in another embodiment, the calcination temperature is about250° C. to about 900° C.; and in yet another embodiment, the calcinationtemperature is about 300° C. to 600° C. The calcination time is, in oneembodiment, about one hour to about seventy-two hours.

While many methods and machines are known to those skilled in the artfor fractionating particles into discreet sizes and determining particlesize distribution, sieving is one of the easiest, least expensive, andcommon ways. An alternative way to determine the size distribution ofparticles is with light scattering. Following calcination, the catalystis, in one embodiment, ground and sieved to provide a more uniformproduct. The particle size distribution of the catalyst particlesincludes a particle span that, in one embodiment, is less than about 3;in another embodiment, the particle size distribution of the catalystparticles includes a particle span that is less than about 2; and in yetanother embodiment, the particle size distribution of the catalystparticles includes a particle span that is less than about 1.5. Inanother embodiment of the invention, the catalyst is sieved to a medianparticle size of about 50 μm to about 500 μm. In another embodiment ofthe invention, the catalyst is sieved to a median particle size of about100 μm to about 200 μm.

In another embodiment, the catalyst is prepared by the following steps,which comprise: (a) combining a phosphorus containing compound, anitrate salt, phosphoric acid, and water to form a wet mixture, whereinthe molar ratio between phosphorus and the cations in both saidphosphorus containing compound and said nitrate salt is about 1, (b)calcining said wet mixture stepwise at about 50° C., about 80° C., about120° C., and about 450° C. to about 550° C. to produce a dried solid,and (c) grinding and sieving said dried solid to about 100 μm to about200 μm, to produce said catalyst.

In another embodiment, the catalyst is prepared by the following steps,which comprise: (a) combining MnPO₄.qH₂O, KNO₃, and H₃PO₄, in a molarratio of about 0.3:1:1, on an anhydrous basis, and water to give a wetmixture, (b) calcining said wet mixture stepwise at about 50° C., about80° C., about 120° C., and about 450° C. to about 550° C. to give adried solid, and (c) grinding and sieving said dried solid to about 100μm to about 200 μm, to produce said catalyst.

In another embodiment, the catalyst is prepared by the following steps,which comprise: (a) combining Ca₂P₂O₇, KNO₃, and H₃PO₄, in a molar ratioof about 1.6:1:1, and water to give a wet mixture, (b) calcining saidwet mixture stepwise at about 50° C., about 80° C., about 120° C., andabout 450° C. to about 550° C. to give a dried solid, and (c) grindingand sieving said dried solid to about 100 μm to about 200 μm, to producesaid catalyst.

In another embodiment, the catalyst is prepared by the following steps,which comprise: (a) combining a phosphorus containing compound, anitrate salt, phosphoric acid, and water to give a wet mixture, whereinthe molar ratio between phosphorus and the cations in both thephosphorus containing compound and nitrate salt is about 1, (b) heatingsaid wet mixture to about 80° C. with stirring until near dryness toform a wet solid, (c) calcining said wet solid stepwise at about 50° C.,about 80° C., about 120° C., and about 450° C. to about 550° C. to givea dried solid, and (d) grinding and sieving said dried solid to about100 μm to about 200 μm, to produce said catalyst.

In another embodiment, the catalyst is prepared by the following steps,which comprise: (a) combining Ba(NO₃)₂, K₂HPO₄, and H₃PO₄, in a molarratio of about 3:1:4, and water to give a wet mixture, (b) heating saidwet mixture to about 80° C. with stirring until near dryness to form awet solid, (c) calcining said wet solid stepwise at about 50° C., about80° C., about 120° C., and about 450° C. to about 550° C. to give adried solid, and (d) grinding and sieving said dried solid to about 100μm to about 200 μm, to produce said catalyst.

In another embodiment, the catalyst is prepared by the following steps,which comprise: (a) combining Mn(NO₃)₂.4H₂O, K₂HPO₄, and H₃PO₄, in amolar ratio of about 1:1.5:2, and water to give a wet mixture, (b)heating said wet mixture to about 80° C. with stirring until neardryness to form a wet solid, (c) calcining said wet solid stepwise atabout 50° C., about 80° C., about 120° C., and about 450° C. to about550° C. to give a dried solid, and (d) grinding and sieving said driedsolid to about 100 μm to about 200 μm, to produce said catalyst.

In another embodiment, the catalyst is prepared by the following steps,which comprise: (a) combining Ca₂P₂O₇ and KH₂PO₄ in a molar ratio ofabout 3:1 to give a solid mixture, and (b) calcining said solid mixturestepwise at about 50° C., about 80° C., about 120° C., and about 450° C.to about 550° C., to produce said catalyst.

Following calcination and optional grinding and sieving, the catalystcan be utilized to catalyze several chemical reactions. Non-limitingexamples of reactions are: dehydration of hydroxypropionic acid toacrylic acid (as described in further detail below), dehydration ofglycerin to acrolein, dehydration of aliphatic alcohols to alkenes orolefins, dehydrogenation of aliphatic alcohols to ethers, otherdehydrogenations, hydrolyses, alkylations, dealkylations, oxidations,disproportionations, es terific ations , cyclizations, isomerizations,condensations, aromatizations, polymerizations, and other reactions thatmay be apparent to those having ordinary skill in the art.

V Process for the Production of Acrylic Acid or Its Derivatives fromHydroxypropionic Acid or Its Derivatives

A process for converting hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof to acrylic acid, acrylic acidderivatives, or mixtures thereof of the present invention comprises thefollowing steps: a) providing an aqueous solution comprisinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof, wherein said hydroxypropionic acid is in monomeric form in theaqueous solution; b) combining the aqueous solution with an inert gas toform an aqueous solution/gas blend; c) evaporating the aqueous solutiongas/blend to produce a gaseous mixture; and d) dehydrating the gaseousmixture by contacting the mixture with a dehydration catalyst under apressure of at least about 80 psig.

Hydroxypropionic acid can be 3-hydroxypropionic acid, 2-hydroxypropionicacid (also called, lactic acid), 2-methyl hydroxypropionic acid, ormixtures thereof. Derivatives of hydroxypropionic acid can be metal orammonium salts of hydroxypropionic acid, alkyl esters ofhydroxypropionic acid, alkyl esters of 2-methyl hydroxypropionic acid,cyclic di-esters of hydroxypropionic acid, hydroxypropionic acidanhydride, or a mixture thereof. Non-limiting examples of metal salts ofhydroxypropionic acid are sodium hydroxypropionate, potassiumhydroxypropionate, and calcium hydroxypropionate. Non-limiting examplesof alkyl esters of hydroxypropionic acid are methyl hydroxypropionate,ethyl hydroxypropionate, butyl hydroxypropionate, 2-ethylhexylhydroxypropionate, or mixtures thereof. A non-limiting example of cyclicdi-esters of hydroxypropionic acid is dilactide.

Hydroxypropionic acid can be in monomeric form or as oligomers in anaqueous solution of hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof. In one embodiment, the oligomers ofthe hydroxypropionic acid in an aqueous solution of hydroxypropionicacid, hydroxypropionic acid derivatives, or mixtures thereof are lessthan about 25 wt % based on the total amount of hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof. In anotherembodiment, the oligomers of the hydroxypropionic acid in an aqueoussolution of hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof are less than about 10 wt % based on the total amountof hydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof. In another embodiment, the oligomers of the hydroxypropionicacid in an aqueous solution of hydroxypropionic acid, hydroxypropionicacid derivatives, or mixtures thereof are less than about 5 wt % basedon the total amount of hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof. In yet another embodiment, thehydroxypropionic acid is in monomeric form in an aqueous solution ofhydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof. The process steps to remove the oligomers from the aqueoussolution can be purification or diluting with water and heating. In oneembodiment, the heating step can involve heating the aqueous solution ofhydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof at a temperature from about 50° C. to about 100° C. to removethe oligomers of the hydroxypropionic acid. In another embodiment, theheating step can involve heating the lactic acid aqueous solution at atemperature from about 95° C. to about 100° C. to remove the oligomersof the lactic acid and produce a monomeric lactic acid aqueous solutioncomprising at least 95 wt % of lactic acid in monomeric form based onthe total amount of lactic acid. In another embodiment, an about 88 wt %lactic acid aqueous solution (e.g. from Purac Corp., Lincolnshire, Ill.)is diluted with water to form an about 20 wt % lactic acid aqueoussolution, to remove the ester impurities that are produced from theintermolecular condensation reaction. These esters can result in loss ofproduct due to their high boiling point and oligomerization in theevaporation stage of the process. Additionally, these esters can causecoking, catalyst deactivation, and reactor plugging. As the watercontent decreases in the aqueous solution, the loss of feed material tothe catalytic reaction, due to losses in the evaporation step,increases.

In one embodiment, the hydroxypropionic acid is lactic acid or 2-methyllactic acid. In another embodiment, the hydroxypropionic acid is lacticacid. Lactic acid can be L-lactic acid, D-lactic acid, or mixturesthereof. In one embodiment, the hydroxypropionic acid derivative ismethyl lactate. Methyl lactate can be neat or in an aqueous solution.

Acrylic acid derivatives can be metal or ammonium salts of acrylic acid,alkyl esters of acrylic acid, acrylic acid oligomers, or a mixturethereof. Non-limiting examples of metal salts of acrylic acid are sodiumacrylate, potassium acrylate, and calcium acrylate. Non-limitingexamples of alkyl esters of acrylic acid are methyl acrylate, ethylacrylate, butyl acrylate, 2-ethylhexyl acrylate, or mixtures thereof.

In one embodiment, the concentration of the hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof in the aqueoussolution is between about 5 wt % and about 50 wt %. In anotherembodiment, the concentration of the hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof in the aqueoussolution is between about 10 wt % and about 25 wt %. In yet anotherembodiment, the concentration of the hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof in the aqueoussolution is about 20 wt %.

The aqueous solution can be combined with an inert gas to form anaqueous solution/gas blend. Non-limiting examples of the inert gas areair, nitrogen, helium, argon, carbon dioxide, carbon monoxide, steam,and mixtures thereof. The inert gas can be introduced to the evaporatingstep separately or in combination with the aqueous solution. The aqueoussolution can be introduced with a simple tube or through atomizationnozzles. Non-limiting examples of atomization nozzles include fannozzles, pressure swirl atomizers, air blast atomizers, two-fluidatomizers, rotary atomizers, and supercritical carbon dioxide atomizers.In one embodiment, the droplets of the aqueous solution are less thanabout 500 μm in diameter. In another embodiment, the droplets of theaqueous solution are less than about 200 μm in diameter. In yet anotherembodiment, the droplets of the aqueous solution are less than about 100μm in diameter.

In the evaporating step, the aqueous solution/gas blend is heated togive a gaseous mixture. In one embodiment, the temperature during theevaporating step is from about 165° C. to about 450° C. In anotherembodiment, the temperature during the evaporating step is from about250° C. to about 375° C. In one embodiment, the gas hourly spacevelocity (GHSV) in the evaporating step is from about 720 h⁻¹ to 3,600h⁻¹. In another embodiment, the gas hourly space velocity (GHSV) in theevaporating step is about 7,200 h⁻¹. The evaporating step can beperformed at either atmospheric pressure or higher pressure. In oneembodiment, the evaporating step is performed under a pressure fromabout 80 psig to about 550 psig. In another embodiment, the evaporatingstep is performed under a pressure from about 300 psig to about 400psig. In yet another embodiment, the evaporating step is performed undera pressure from about 350 psig to about 375 psig. In one embodiment, thegaseous mixture comprises from about 0.5 mol % to about 50 mol %hydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof. In another embodiment, the gaseous mixture comprises from about1 mol % to about 10 mol % hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof. In another embodiment, the gaseousmixture comprises from about 1.5 mol % to about 3.5 mol %hydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof. In another embodiment, the gaseous mixture comprises about 2.5mol % hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof.

The evaporating step can be performed in various types of equipment,such as, but not limited to, plate heat exchanger, empty flow reactor,and fixed bed flow reactor. Regardless of the type of the reactor, inone embodiment, the reactor has an interior surface comprising materialselected from the group consisting of quartz, borosilicate glass,silicon, hastelloy, inconel, manufactured sapphire, stainless steel, andmixtures thereof. In another embodiment, the reactor has an interiorsurface comprising material selected from the group consisting ofquartz, borosilicate glass, and mixtures thereof. The evaporating stepcan be performed in a reactor with the aqueous solution flowing down, orflowing up, or flowing horizontally. In one embodiment, the evaporatingstep is performed in a reactor with the aqueous solution flowing down.Also, the evaporating step can be done in a batch form.

The gaseous mixture from the evaporating step is converted to acrylicacid, acrylic acid derivatives, and mixture thereof by contact it with adehydration catalyst in the dehydrating step. The dehydration catalystcan be selected from the group comprising sulfates, phosphates, metaloxides, aluminates, silicates, aluminosilicates (e.g., zeolites),arsenates, nitrates, vanadates, niobate s , tantalates , selenates,arsenatophosphates , phosphoaluminates, phosphoborates, phosphocromates, phosphomolybdates, phospho silicate s , pho spho sulfates ,phosphotungstates, and mixtures thereof, and others that may be apparentto those having ordinary skill in the art. The catalyst can contain aninert support that is constructed of a material comprising silicates,aluminates, carbons, metal oxides, and mixtures thereof. In oneembodiment, the dehydrating step is performed in a reactor, wherein thereactor has an interior surface comprising material selected from thegroup consisting of quartz, borosilicate glass, silicon, hastelloy,inconel, manufactured sapphire, stainless steel, and mixtures thereof.In another embodiment, the dehydrating step is performed in a reactor,wherein the reactor has an interior surface comprising material selectedfrom the group consisting of quartz, borosilicate glass, and mixturesthereof. In one embodiment, the temperature during the dehydrating stepis from about 150° C. to about 500° C. In another embodiment, thetemperature during the dehydrating step is from about 300° C. to about450° C. In one embodiment, the GHSV in the dehydrating step is fromabout 720 h⁻¹ to about 36,000 h⁻¹. In another embodiment, the GHSV inthe dehydrating step is about 3,600 h⁻¹. The dehydrating step can beperformed at higher than atmospheric pressure. In one embodiment, thedehydrating step is performed under a pressure of at least about 80psig. In another embodiment, the dehydrating step is performed under apressure from about 80 psig to about 550 psig. In another embodiment,the dehydrating step is performed under a pressure from about 150 psigto about 500 psig. In yet another embodiment, the dehydrating step isperformed under a pressure from about 300 psig to about 400 psig. Thedehydrating step can be performed in a reactor with the gaseous mixtureflowing down, flowing up, or flowing horizontally. In one embodiment,the dehydrating step is performed in a reactor with the gaseous mixtureflowing down. Also, the dehydrating step can be done in a batch form.

In one embodiment, the evaporating and dehydrating steps are combined ina single step. In another embodiment, the evaporating and dehydratingsteps are performed sequentially in a single reactor. In yet anotherembodiment, the evaporating and dehydrating steps are performedsequentially in a tandem reactor.

In one embodiment, the selectivity of acrylic acid, acrylic acidderivatives, and mixture thereof from hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof is at least about50%. In another embodiment, the selectivity of acrylic acid, acrylicacid derivatives, and mixture thereof from hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof is at least about80%. In one embodiment, the selectivity of propanoic acid fromhydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof is less than about 5%. In another embodiment, the selectivity ofpropanoic acid from hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof is less than about 1%. In oneembodiment, the conversion of the hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof is more thanabout 50%. In another embodiment, the conversion of the hydroxypropionicacid, hydroxypropionic acid derivatives, or mixtures thereof is morethan about 80%.

In another embodiment of the present invention, a process for convertinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof to acrylic acid, acrylic acid derivatives, or mixtures thereofis provided. The process comprises the following steps: a) providing anaqueous solution comprising hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof, wherein said hydroxypropionic acidcomprises oligomers in said aqueous solution; b) heating the aqueoussolution at a temperature from about 50° C. to about 100° C. to removethe oligomers of the hydroxypropionic acid and produce an aqueoussolution of monomeric hydroxypropionic acid; c) combining the aqueoussolution of monomeric hydroxypropionic acid with an inert gas to form anaqueous solution/gas blend; d) evaporating the aqueous solutiongas/blend to produce a gaseous mixture; and e) dehydrating the gaseousmixture by contacting the mixture with a dehydration catalyst andproducing said acrylic acid, acrylic acid derivatives, or mixturesthereof.

In one embodiment, after the heating step, the concentration of theoligomers of the hydroxypropionic acid in the aqueous solution ofmonomeric of monomeric hydroxypropionic acid is less than about 20 wt %based on the total amount of hydroxypropionic acid, hydroxypropionicacid derivatives, or mixtures thereof. In another embodiment, after theheating step, the concentration of the oligomers of the hydroxypropionicacid in the aqueous solution of monomeric of monomeric hydroxypropionicacid is less than about 5 wt % based on the total amount ofhydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof.

In another embodiment of the present invention, a process for convertinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof to acrylic acid, acrylic acid derivatives, and mixture thereofis provided. The process comprises the following steps: a) providing anaqueous solution comprising hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof, wherein said hydroxypropionic acid isin monomeric form in said aqueous solution; b) combining the aqueoussolution with an inert gas to form an aqueous solution/gas blend; c)evaporating the aqueous solution/gas blend to produce a gaseous mixture;d) dehydrating the gaseous mixture by contacting the mixture with adehydration catalyst producing acrylic acid, and/or acrylates; and e)cooling the acrylic acid, acrylic acid derivatives, and mixture thereofat a GHSV of more than about 360 h⁻¹.

The stream of acrylic acid, acrylic acid derivatives, and mixturethereof produced in the dehydrating step is cooled to give an aqueousacrylic acid composition as the product stream. The time required tocool stream of the acrylic acid, acrylic acid derivatives, or mixturesthereof must be controlled to reduce the decomposition of acrylic acidto ethylene and polymerization. In one embodiment, the GHSV of theacrylic acid, acrylic acid derivatives, and mixture thereof in thecooling step is more than about 720 h⁻.

In another embodiment of the present invention, a process for convertinglactic acid to acrylic acid is provided. The process comprises thefollowing steps: a) diluting an about 88 wt % lactic acid aqueoussolution with water to form an about 20 wt % lactic acid aqueoussolution; b) heating said about 20 wt % lactic acid aqueous solution ata temperature of about 95° C. to about 100° C. to remove oligomers ofsaid lactic acid, producing a monomeric lactic acid solution comprisingat least about 95 wt % of said lactic acid in monomeric form based onthe total amount of lactic acid; c) combining said monomeric lactic acidsolution with nitrogen to form an aqueous solution/gas blend; d)evaporating said aqueous solution/gas blend in a reactor with insidesurface of borosilicate glass at a GHSV of about 7,200 h⁻¹ at atemperature from about 300° C. to about 350° C. to produce a gaseousmixture comprising about 2.5 mol % lactic acid and about 50 mol % water;e) dehydrating said gaseous mixture in a reactor with inside surface ofborosilicate glass at a GHSV of about 3,600 h⁻¹ at a temperature of 350°C. to about 425° C. by contacting said mixture with a dehydrationcatalyst under a pressure of about 360 psig, producing said acrylicacid; and f) cooling said acrylic acid at a GHSV from about 360 h⁻¹ toabout 36,000 h⁻¹.

In another embodiment of the present invention, a process for convertinghydroxypropionic acid, derivatives of hydroxypropionic acid, andmixtures thereof to acrylic acid, acrylic acid derivatives, or mixturesthereof is provided. The process comprises the following steps: a)providing an aqueous solution comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof, wherein saidhydroxypropionic acid is in monomeric form in said aqueous solution, andwherein the hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof comprise from about 10 wt % to about 25 wt % of saidaqueous solution; b) combining said aqueous solution with an inert gasto form an aqueous solution/gas blend; c) evaporating said aqueoussolution/gas blend to produce a gaseous mixture; and d) dehydrating saidgaseous mixture by contacting said mixture with a dehydration catalystproducing acrylic acid, acrylic acid derivatives, or mixtures thereof.

In another embodiment of the present invention, a process for convertingalkyl lactates to acrylic acid, acrylic acid derivatives, or mixturesthereof is provided. The process comprises the following steps: a)providing alkyl lactates or a solution comprising alkyl lactates and asolvent; b) combining said alkyl lactates or said solution comprisingsaid alkyl lactates and said solvent with an inert gas to form aliquid/gas blend; c) evaporating said liquid/gas blend to produce agaseous mixture; and d) dehydrating said gaseous mixture by contactingsaid gaseous mixture with a dehydration catalyst under a pressure of atleast about 80 psig, producing acrylic acid, acrylic acid derivatives,or mixtures thereof.

In one embodiment, alkyl lactates are selected from the group consistingof methyl lactate, ethyl lactate, butyl lactate, 2-ethylhexyl lactate,and mixtures thereof. In another embodiment, the solvent is selectedfrom the group consisting of water, methanol, ethanol, butanol,2-ethylhexanol, isobutanol, isooctyl alcohol, and mixtures thereof.

In another embodiment, a process for converting hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof to acrylic acid,acrylic acid derivatives, or mixtures thereof is provided comprising thefollowing steps: a) providing a solution comprising hydroxypropionicacid, hydroxypropionic acid derivatives, or mixtures thereof; b)combining the solution with a gas to form a solution/gas blend; and c)dehydrating the solution/gas blend by contacting the solution/gas blendwith a dehydration catalyst.

VI EXAMPLES

The following examples are provided to illustrate the invention, but arenot intended to limit the scope thereof.

Example 1

Solid dibasic potassium phosphate, K₂HPO₄ (36.40 g, 209 mmol, ≧98%;Sigma-Aldrich Co., St. Louis, Mo.; catalog # P3786) was mixed quicklywith an aqueous solution of barium nitrate, Ba(NO₃)₂ (2050 mL of a 0.08g/mL stock solution, 627 mmol, 99.999%; Sigma-Aldrich Co., St. Louis,Mo.; catalog # 202754) at room temperature. Phosphoric acid, H₃PO₄ (58.7mL of an 85 wt %, density=1.684 g/mL, 857 mmol; Acros Organics, Geel,Belgium; catalog # 295700010), was added to the slurry, providing asolution containing potassium (K⁺, M^(I)) and barium (Ba²⁺, M^(II))cations. The final pH of the suspension was about 1.6. Theacid-containing suspension was then dried slowly in a glass beaker at80° C. using a heating plate while magnetically stirring the suspensionuntil the liquid was evaporated and the material was almost completelydried. Heating was continued in a oven with air circulation (G1530A,HP6890 GC; Agilent Corp., Santa Clara, Calif.) at 50° C. for 5.3 h, thenat 80° C. for 10 h (0.5° C./min ramp), following by cooling down at 25°C. The material was calcined at 120° C. for 2 hours (0.5° C./min ramp)followed by 450° C. for 4 hours (2° C./min ramp) using the same oven.After calcination, the material was left inside the oven until it cooleddown by itself at a temperature below 25° C. before it was taken out ofthe oven. Finally, the catalyst was ground and sieved to about 100 μm toabout 200 μm.

Example 2

454 g of an 88 wt % L-lactic acid solution (Purac Corp., Lincolnshire,Ill.) was diluted with 1,300 g of water. The diluted solution was heatedto 95° C. and held at that temperature with stirring for about 4 to 12hours. Then, the solution was cooled to room temperature, and its lacticacid and lactic acid oligomers concentrations were measured by HPLC(Agilent 1100 system; Santa Clara, Calif.) equipped with a DAD detectorand a Waters Atlantis T3 column (Catalog # 186003748; Milford, Mass.)using methods generally known by those having ordinary skill in the art.The solution was essentially free of oligomers. Finally, the solutionwas further diluted with water to yield a 20 wt % L-lactic acid aqueoussolution and essentially free of oligomers.

Example 3

The reactor consisted of an electric clam shell furnace (Applied Testsystems, Butler, Pa.) with an 8″ (20.3 cm) heated zone with onetemperature controller connected in series to another electric clamshell furnace (Applied Test Systems, Butler, Pa.) with a 16″ (40.6 cm)heated zone containing two temperature controllers and a reactor tube.The reactor tube consisted of a 13″ (33 cm) borosilicate glass-linedtube (SGE Analytical Science Pty Ltd., Ringwood, Australia)) and a 23″(58.4 cm) borosilicate glass lined tube connected in series using aSwagelok™ tee fitting equipped with an internal thermocouple and havingan inside diameter of 9.5 mm The head of the column was fitted with a ⅛″(3.2 mm) stainless steel nitrogen feed line and a 1/16″ (1.6 mm) fusedsilica lined stainless steel liquid feed supply line connected to a HPLCpump (Smartline 100, Knauer, Berlin, Germany) that was connected to alactic acid feed tank. The bottom of the reactor was connected to aTeflon-lined catch tank using ⅛″ (3.2 mm) fused silica lined stainlesssteel tubing and Swagelok™ fittings. The reactor column was packed witha plug of glass wool, 13 g of fused quartz, 16″ (40.7 cm) with catalystof Example 1 (47 g and 28.8 mL packed bed volume) and topped with 25 gof fused quartz. The reactor tube was placed in an aluminum block andplaced into the reactor from above in a downward flow. The reactor waspreheated to 375° C. overnight under 0.25 L/min nitrogen. The nitrogenfeed was increased to 0.85 L/min during the experiment. The liquid feedwas a 20 wt % aqueous solution of L-lactic acid, prepared as in Example2, and fed at 0.845 mL/min (LHSV of 1.8 h⁻¹; 50.7 g/h), giving aresidence time of about 1 s (GHSV of 3,600 h⁻¹) at STP conditions. Theclam shell heaters were adjusted to give an internal temperature about350° C. After flowing through the reactor, the gaseous stream was cooledand the liquid was collected in the catch tank for analysis by off-lineHPLC using an Agilent 1100 system (Santa Clara, Calif.) equipped with aDAD detector and a Waters Atlantis T3 column (Catalog # 186003748;Milford, Mass.) using methods generally known by those having ordinaryskill in the art. The gaseous stream was analyzed on-line by GC using anAgilent 7890 system (Santa Clara, Calif.) equipped with a FID detectorand Varian CP-Para Bond Q column (Catalog # CP7351; Santa Clara,Calif.). The crude reaction mixture was cooled and collected over 159 hto give 748 g acrylic acid as a crude mixture in 54% yield, 75% acrylicacid selectivity, and 69% conversion of lactic acid. The acrylic acidyield, corrected for the losses during the evaporating step, was 61% andits selectivity was 89%. The acrylic acid aqueous concentration was 8.4wt %, and that of lactic acid was 6.3 wt %.

Example 4

The reaction mixtures from Example 3 were combined into four batches andisolated to give an acrylic acid solution of 668.9 g of acrylic acid inwater. A stabilizer (200-400 ppm phenothiazine) was added to each batchand the batches were extracted with ethyl acetate several times. Thecombined ethyl acetate layers were dried with sodium sulfate, treatedwith activated carbon, filtered over diatomaceous earth, and washed withethyl acetate. The filtrate was evaporated at 40-70 mm Hg with a bathtemperature of 23° C.-40° C. to give bio-based acrylic acid as a paleyellow liquid (81.4% yield). The bio-based acrylic acid was thenfractionally distilled at 40 mm Hg using a 12 inch 14/20 Vigreux column.The product was collected with head temperature of 59° C.-62° C.,stabilized with 4-methoxy phenol, and placed in a 3° C.-5° C. fridgeovernight. The solution was removed from the fridge and thawed. Theresulting liquid was decanted off and the solids were combined. Thecrystallization was repeated several times. The four batches werecombined to give glacial acrylic acid (218 g, 32.6% yield onpurification). The glacial acrylic acid composition consisted of 99.1 wt% acrylic acid, 0.1 wt % water, 0.7 wt % propanoic acid, and 0.1 wt %lactic acid.

Example 5

The bio-based content of the glacial acrylic acid composition of Example4 is measured in accordance with ASTM D6866 Method B, as described inthe Test and Calculation Procedures section below, and is greater thanabout 90%.

VII Test and Calculation Procedures

The bio-based content of a material is measured using the ASTM D6866method, which allows the determination of the bio-based content ofmaterials using radiocarbon analysis by accelerator mass spectrometry,liquid scintillation counting, and isotope mass spectrometry. Whennitrogen in the atmosphere is struck by an ultraviolet light producedneutron, it loses a proton and forms carbon that has a molecular weightof 14, which is radioactive. This ¹⁴C is immediately oxidized intocarbon dioxide, which represents a small, but measurable fraction ofatmospheric carbon. Atmospheric carbon dioxide is cycled by green plantsto make organic molecules during the process known as photosynthesis.The cycle is completed when the green plants or other forms of lifemetabolize the organic molecules producing carbon dioxide, which causesthe release of carbon dioxide back to the atmosphere. Virtually allforms of life on Earth depend on this green plant production of organicmolecules to produce the chemical energy that facilitates growth andreproduction. Therefore, the ¹⁴C that exists in the atmosphere becomespart of all life forms and their biological products. These renewablybased organic molecules that biodegrade to carbon dioxide do notcontribute to global warming because no net increase of carbon isemitted to the atmosphere. In contrast, fossil fuel-based carbon doesnot have the signature radiocarbon ratio of atmospheric carbon dioxide.See WO 2009/155086, incorporated herein by reference.

The application of ASTM D6866 to derive a “bio-based content” is builton the same concepts as radiocarbon dating, but without use of the ageequations. The analysis is performed by deriving a ratio of the amountof radiocarbon (¹⁴C) in an unknown sample to that of a modern referencestandard. The ratio is reported as a percentage with the units “pMC”(percent modern carbon). If the material being analyzed is a mixture ofpresent day radiocarbon and fossil carbon (containing no radiocarbon),then the pMC value obtained correlates directly to the amount of biomassmaterial present in the sample. The modern reference standard used inradiocarbon dating is a NIST (National Institute of Standards andTechnology) standard with a known radiocarbon content equivalentapproximately to the year AD 1950. The year AD 1950 was chosen becauseit represented a time prior to thermo-nuclear weapons testing, whichintroduced large amounts of excess radiocarbon into the atmosphere witheach explosion (termed “bomb carbon”). The AD 1950 reference represents100 pMC. “Bomb carbon” in the atmosphere reached almost twice normallevels in 1963 at the peak of testing and prior to the treaty haltingthe testing. Its distribution within the atmosphere has beenapproximated since its appearance, showing values that are greater than100 pMC for plants and animals living since AD 1950. The distribution ofbomb carbon has gradually decreased over time, with today's value beingnear 107.5 pMC. As a result, a fresh biomass material, such as corn,could result in a radiocarbon signature near 107.5 pMC.

Petroleum-based carbon does not have the signature radiocarbon ratio ofatmospheric carbon dioxide. Research has noted that fossil fuels andpetrochemicals have less than about 1 pMC, and typically less than about0.1 pMC, for example, less than about 0.03 pMC. However, compoundsderived entirely from renewable resources have at least about 95 percentmodern carbon (pMC), and may have at least about 99 pMC, including about100 pMC.

Combining fossil carbon with present day carbon into a material willresult in a dilution of the present day pMC content. By presuming that107.5 pMC represents present day biomass materials and 0 pMC representspetroleum derivatives, the measured pMC value for that material willreflect the proportions of the two component types. A material derived100% from present day soybeans would give a radiocarbon signature near107.5 pMC. If that material was diluted with 50% petroleum derivatives,it would give a radiocarbon signature near 54 pMC.

A bio-based content result is derived by assigning 100% equal to 107.5pMC and 0% equal to 0 pMC. In this regard, a sample measuring 99 pMCwill give an equivalent bio-based content result of 93%.

Assessment of the materials described herein was done in accordance withASTM D6866, particularly with Method B. The mean values encompass anabsolute range of 6% (plus and minus 3% on either side of the bio-basedcontent value) to account for variations in end-component radiocarbonsignatures. It is presumed that all materials are present day or fossilin origin and that the desired result is the amount of bio-component“present” in the material, not the amount of bio-material “used” in themanufacturing process.

Other techniques for assessing the bio-based content of materials aredescribed in U.S. Pat. Nos. 3,885155, 4,427,884, 4,973,841, 5,438,194,and 5,661,299, and WO 2009/155086, each incorporated herein byreference.

For example, acrylic acid contains three carbon atoms in its structuralunit. If acrylic acid is derived from a renewable resource, then ittheoretically has a bio-based content of 100%, because all of the carbonatoms are derived from a renewable resource.

The foregoing description is given for clearness of understanding only,and no unnecessary limitations should be understood therefrom, asmodifications within the scope of the invention may be apparent to thosehaving ordinary skill in the art.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A composition of crude acrylic acid comprisingbetween about 94 wt % and about 98 wt % acrylic acid, and wherein aportion of the remaining impurities in said composition of crude acrylicacid is hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof.
 2. The composition of claim 1, wherein thehydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof is lactic acid, lactic acid derivatives, or mixtures thereof. 3.A crude acrylic acid composition produced by the steps comprising: a.Providing an aqueous solution of acrylic acid comprising: 1) acrylicacid; and 2) lactic acid, lactic acid derivatives, or mixtures thereof,and wherein said aqueous solution of acrylic acid is essentially free ofmaleic anhydride, furfural, and formic acid; b. Extracting said aqueoussolution of acrylic acid with a solvent to produce an extract; c. Dryingsaid extract to produce a dried extract; d. Distilling said driedextract to produce a distilled acrylic acid composition; and e.Determining the acrylic acid purity of said distilled acrylic acidcomposition, and if the purity is less than about 94 wt % acrylic acid,repeating said distilling step on the purified acrylic acid compositionuntil a purity of about 94 wt % acrylic acid is achieved and said crudeacrylic acid composition is produced.
 4. The composition of claim 3,wherein the aqueous solution of acrylic acid comprises from about 4 wt %to about 80 wt % acrylic acid.
 5. The composition of claim 3, whereinthe aqueous solution of acrylic acid comprises from about 5 wt % toabout 25 wt % acrylic acid.
 6. The composition of claim 3, wherein theaqueous solution of acrylic acid comprises from about 0.001 wt % toabout 50 wt % lactic acid, lactic acid derivatives, or mixtures thereof.7. The composition of claim 3, wherein the aqueous solution of acrylicacid comprises from about 0.001 wt % to about 20 wt % lactic acid,lactic acid derivatives, or mixtures thereof.
 8. The composition ofclaim 3, wherein said solvent is selected from the group consisting ofethyl acetate, isobutyl acetate, methyl acetate, toluene, dimethylphthalate, hexane, pentane, diphenyl ether, ethyl hexanoic acid,N-methylpyrrolidone, C6 to C10 paraffin fractions, and mixtures thereof.9. The composition of claim 3, wherein said drying is performed byazeotropic distillation.
 10. The composition of claim 3, wherein saiddrying is performed by distillation.
 11. The composition of claim 3,wherein said drying is performed by sorption.
 12. The composition ofclaim 11, wherein said sorption is performed on a solid powder selectedfrom the group consisting of magnesium sulfate, sodium sulfate, calciumsulfate, molecular sieves, metal hydrides, reactive metals, and mixturesthereof.
 13. A crude acrylic acid composition produced by the stepscomprising: a. Providing an aqueous solution of acrylic acidcomprising: 1) acrylic acid; and 2) lactic acid, lactic acidderivatives, or mixtures thereof, and wherein said aqueous solution ofacrylic acid is essentially free of maleic anhydride, furfural, andformic acid; b. Extracting said aqueous solution of acrylic acid with asolvent to produce an extract; c. Drying said extract to produce a driedextract; d. Distilling said dried extract to produce a distilled acrylicacid composition; e. Cooling said distilled acrylic acid composition toa temperature from about −21° C. to about 14° C. to produce crystals ofacrylic acid; f. Partially melting said crystals of acrylic acid toproduce a liquid/solid mixture; g. Decanting said liquid/solid mixtureto produce a purified acrylic acid solid composition; h. Fully meltingsaid purified acrylic acid solid composition to produce a purifiedacrylic acid liquid composition; and i. Determining the acrylic acidpurity of said purified acrylic acid liquid composition, and if thepurity is less than about 94 wt % acrylic acid, repeating said cooling,partially melting, decanting, and fully melting steps on the purifiedacrylic acid liquid composition until a purity of about 94 wt % acrylicacid is achieved and said crude acrylic acid composition is produced.14. The composition of claim 13, wherein the aqueous solution of acrylicacid comprises from about 4 wt % to about 80 wt % acrylic acid.
 15. Thecomposition of claim 13, wherein the aqueous solution of acrylic acidcomprises from about 5 wt % to about 25 wt % acrylic acid.
 16. Thecomposition of claim 13, wherein the aqueous solution of acrylic acidcomprises from about 0.001 wt % to about 50 wt % lactic acid, lacticacid derivatives, or mixtures thereof.
 17. The composition of claim 13,wherein the aqueous solution of acrylic acid comprises from about 0.001wt % to about 20 wt % lactic acid, lactic acid derivatives, or mixturesthereof.
 18. The composition of claim 13, wherein said solvent isselected from the group consisting of ethyl acetate, isobutyl acetate,methyl acetate, toluene, dimethyl phthalate, hexane, pentane, diphenylether, ethyl hexanoic acid, N-methylpyrrolidone, C6 to C10 paraffinfractions, and mixtures thereof.
 19. The composition of claim 13,wherein said drying is performed by azeotropic distillation.
 20. Thecomposition of claim 13, wherein said drying is performed bydistillation.
 21. The composition of claim 13, wherein said drying isperformed by sorption.
 22. The composition of claim 21, wherein saidsorption is performed on a solid powder selected from the groupconsisting of magnesium sulfate, sodium sulfate, calcium sulfate,molecular sieves, metal hydrides, reactive metals, and mixtures thereof.